Effect of finite lateral size of dielectric grating on optical bound state in the continuum

Abstract

Optical bound states in the continuum (BIC) are localized states with energy lying above the light line and having infinite lifetime. Any losses taking place in real systems result in transformation of the bound states into resonant states with finite lifetime. In this work, we analyze properties of BIC in CMOS-compatible one-dimensional photonic structure based on silicon-on-insulator and silicon nitride wafers. We reveal that finite lateral size of samples could destroy both off-Г BIC and at-Г BIC turning them into resonant states due to in-plane symmetry breaking.